The invention is in the field of the measurement of the Exhaust Gas Temperature (EGT) of a jet engine.
The Exhaust Gas Temperature (EGT) of a jet engine is measured by one or more EGT probes connected to a central EGT measurement control circuit via an electrical harness. Different jet engines and even different models of the same jet engine have different types of EGT probes and EGT electrical harnesses, thereby requiring an airline or a jet engine maintenance shop to keep a considerable inventory of EGT associated spare parts for maintenance purposes.
In accordance with the present invention, there is provided an adapter for enabling the installation of a Type II EGT probe instead of a Type I EGT probe on a Type I jet engine. the Type II EGT probe having probe connectors for connection to an electrical harness, the adapter having a rim defining a through aperture, the adapter being mountable on the Type I jet engine instead of a Type I EGT probe and capable of having the Type II EGT probe mounted thereon whereupon the Type II EGT probe is mounted on the Type I jet engine in substantially the same orientation as it is normally mounted on a Type II jet engine and its probe connectors are accessible via said aperture for connection to its associated electrical harness.
The present invention is based on the realization that if a Type I model of a jet engine can be effectively converted into a Type II model thereof without necessitating engine removal, tear down, and part replacement except for its EGT probes and its associated EGT electrical harnesses, then it is sufficient to have Type II EGT probes and Type II electrical harnesses in stock for use with either Type I or II jet engines as the need arises. The requirements for the effective conversion of a Type I model of a jet engine to a Type II model thereof are as follows: First, a jet engine is available in two models which are identical in every respect except that they have different types and possible number of EGT probes. Second, that the same number of EGT probes employed in a Type II model of a jet engine can replace the original EGT probes in a Type I model to assume substantially the same positions therein as in a Type II model such that an EGT reading yielded in accordance with the Type II EGT configuration is still acceptable in terms of determining the serviceability of the Type I jet engine. One such jet engine which complies with these requirements is the Pratt and Whitney JT9D-7A jet engine which is available in a first model with four Typical Part No. 777925 EGT probes and four Typical Part No. 777928 EGT probes making a total of eight EGT probes and in a second model with six Typical Part No. 761366 EGT probes. Other such jet engines which comply to these requirements include inter alia JT9D-7, JT9D-7H, JT9D-7AH, and JT9D-F.
The present invention also affords another advantage in that the effective conversion of a Type I jet engine to a Type II jet engine may render a higher EGT margin for extending its serviceability, however, without compromising safety considerations to any extent, if at all. Still further, the present invention facilitates back-to-back comparative testing of the same Type I jet engine once with a Type I EGT configuration and once with a Type II EGT configuration, thereby enabling accurate troubleshooting of EGT spread discrepancies by identifiing causes in certain areas of the burners and/or the fuel nozzles, and suitable corrective action.